Centrally controlled illumination networks are being widely used recently, such a control mode allowing the user to control the illumination networks in real time to display different illumination profiles. A main feature of a control system using such a control mode is that the data rates for communication between a console and nodes are asymmetrical, because generally there is only one or a few consoles, comparing to a large number of nodes (thousands or even tens of thousands).
Traditionally, the console and the nodes are connected via cables, and such connection may bring many engineering difficulties and troubles to the system in its installation, commissioning and maintenance. With the development of the wireless communication technique, people began to explore whether a wireless connection can be used to replace the cable so as to eliminate the difficulties and troubles brought about by the wired connection. Although the wireless control system is very attractive, it still has many pending problems concerning display when being applied to an illumination network, for example, the data rate, the communication distance, the cost control and the time needed for commercializing, etc. Theoretically, a brand new wireless control system can be developed specially for the illumination networks, but the high cost and the long time for commercializing will hinder the popularization and application of such a new system.
Therefore, it would be currently a relatively better solution to fully use the existing wireless network protocols. However, the existing wireless network protocols have some serious problems when being directly applied to illumination networks, especially large-scale illumination networks.
Taking an illumination network having one console and 10,000 nodes as an example, it can be supposed that each node comprises a wireless transceiver and 3 colourful (red/green/blue) lamps, the illumination network consisting of said 10,000 nodes forms a screen, which can be used to display video or static images. When video needs to be displayed, each lamp may wirelessly receive 8 bit data from the console within 1/25 second, so an average data rate of a receiver of each node is 8*25*3 bps=600 bps (bit/second); but for a transmitter of the console, its total data rate will be 600*10000 bps=6 Mbps. On the contrary, a transmitter of the node and a receiver of the console only operate occasionally and they transmit information at a very low rate.
Obviously, with respect to such an illumination system mentioned above, the required wireless control could be implemented by either a TDMA (Time Division Multiple Access) system supporting a data rate exceeding 6 Mbps, or an FDMA (Frequency Division Multiple Access) system having more than 10000 frequency channels. However, the TDMA system that can support a data rate exceeding 6 Mbps is too expensive to be suitable for use in such an application, and in practice there is no FDMA system that can simultaneously support 10,000 channels with each channel operating at 600 bps at present, and customizing such FDMA systems to different illumination networks will require a long developing period and a high cost. In addition, expansibility of the TDMA and FDMA systems is very limited.